The long-term objective of the proposed research is to understand how acoustic information can best be encoded for electrical stimulation in cochlear implant patients. The specific aim of this project is to determine the effects rate of stimulation, number of active intra-cochlear electrodes, and threshold mapping strategies on speech perception. Three experiments are proposed to examine these effects. First, comparisons between the three most current cochlear implant devices wilt be made by first matching users of each device on scores in optimal listening conditions and then comparing group performance on tests of speech understanding in difficult listening situations. A second study will evaluate the role of temporal resolution on speech understanding. Subjects will complete a set of experiments in which both output rate and the level of detail in the temporal envelope of speech are manipulated. Outcomes from this study will be used to determine the benefits of representing higher frequencies in the temporal envelope of each channel. The third experiment will assess differences in speech understanding when electrical thresholds are set by standard threshold testing, set to 10% of the maximum comfort level (MCL), and set to electrical values of zero.